That’s not what usually happens.
If there’s at least one unicorn in the world, it’s likely not the only one.
And if one can make a valid English word from seven Scrabble tiles, it’s likely that more than one word can be found.
“Impossible” is a very large set of situations. But once something is possible, it’s unusual for there to be only one way.
If you’re looking for an interesting project, a useful shortcut is finding someone who has already done something similar and then altering or improving it.
No extra points for being the one and only one in your category.